I'm just about to finish up a max recruitment phase and next up is a month of doing 4x4's. While evaluating my goals for coming out of this next phase, I started asking myself if doing a PE phase in the middle of winter is actually worth it, or if I should just go right back into a strength phase. My reasoning is that I live in a mountain town in CO and rarely get outside to climb at all during the winter. Our gym is a very small bouldering-only gym as well.

My concern about doing a PE phase at this point is that after completing the phase of 4x4's I'll simply be going back to bouldering only (which is more power oriented, not PE) until springtime comes or it's time for the next PE phase. Will any gains I make in this first PE phase be completely lost by the next time I will get to use/train it? Would I be better off going right into another round of strength/max recruitment phases and then do a solid PE training phase right before springtime?

PE gains are generally transient. I wouldn't do any 4x4s unless you are training for something specific that requires the type of PE that 4x4s train.

Why did you start your training cycle so early in the year if you have nothing to train for? Ideally you plan your cycle so you peak whe the conditions at your crag are ideal, or to coincide with a climbing trip or something.

Well I started my training phase early because it's winter time and there's not much else I can do in our tiny gym...

My understanding is that the gains from training phases are cumulative (as long as you maintain the systems being trained) so I started training in November so that I could get two full training cycles in throughout the winter and come out climbing strong in the springtime. As I understand, I should be able to start my second strength and max recruitment phases at a higher level than I started the first ones since the bouldering I do in between these phases helps to maintain both of these systems. However, bouldering is not a good way to maintain power endurance, and I'm thinking that the time gap between PE phases will be enough to lose most if not all of the gains I made in the first PE phase. Therefore would it be better to go right back into another set of strength and max recruitment phases to get stronger in the areas that I can maintain in the wintertime and then do a PE phase just prior to my outside climbing season?

To be clear, my goals this coming year are all route related, not bouldering. I'm just limited to bouldering in the wintertime because of the resources available and I'm trying to make the most of my training season.

Therefore would it be better to go right back into another set of strength and max recruitment phases to get stronger in the areas that I can maintain in the wintertime and then do a PE phase just prior to my outside climbing season?

That sounds like the best option, as long as you can stay motivated. Perhaps it might be beneficial to enjoy some bouldering for a few weeks before you begin another cycle.